Dai compared with the TDA and NaOH as catalyst effect. Adding an appropriate amount of TDA
effectively reduced the foam reaction activation energy, reduced reaction temperature, and improved the
TDA's recovery. Due to the severe reaction conditions (high temperature and high pressure), equipment
requirement and conditions are higher. The products of diamine cannot be directly used in the production
of isocyanate. And polyol is also not easily purified, thus making the degradation cost greatly improved,
limiting the utilization of this method in real application.